This invention relates to portable liquid propane gas (LPG) burners, which are used in a great variety of applications. One application is as a heat gun, wherein pressurized gaseous fuel aspirates air for combustion in a jet pump and the combustion products entrain additional air to create a blast of hot air. Such heat guns are commonly used to heat plastic to moderate temperatures to soften it for bending or to shrink it for packaging. To shrink wrap large objects, such as boats, it may be advantageous to lengthen the reach of the heat gun by mounting an extension between the jet pump and the burner. Thus, the ignition system for such heat guns has to be able to adapt to ignite the burner with and without an extension. Present gas-fired heat guns use a spark plug mounted at a side of a burner chamber, which may be difficult to light and also requires electrical wiring outside of the heat gun to power the spark plug. The wiring must be long enough or include couplings and extension wires to accommodate an extension. The spark plug and associated wiring add weight to the heat gun, making it harder to handle and manipulate. Also, the couplings and extension wires increase the likelihood of a short-circuit or of a failure of an electrical connection.